110-11 Effect of Tillage On the Dynamics of Diffusive Phosphate Ions in the Top-Soil.

Poster Number 1014

See more from this Division: S04 Soil Fertility & Plant Nutrition
See more from this Session: Phosphorus and Potassium Management: I
Monday, November 1, 2010
Long Beach Convention Center, Exhibit Hall BC, Lower Level
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Aimé Messiga, Agriculture and Agri-Food Canada, Quebec, QC, Canada, Noura Ziadi, Soils and Crops Research and Development Centre, Agriculture and Agri-Food Canada, Quebec, QC, Canada, Cynthia Grant, Agriculture & Agri-Food Canada, Brandon, MB, Canada, Léon-Etienne Parent, Department of soils and agri-food engineering, Université Laval, Quebec, QC, Canada and Christian Morel, Unité mixte de recherche 1220, Institut national de la recherche agronomique, Bordeaux, France
The dynamics of phosphate ions (Pi) in the rhizosphere of cultivated plants is well described by a mechanistic model that couples the concentration of Pi in solution (Cp) and the diffusive ions of the solid phase (Pr). In the top-soil of no till (NT), there is an accumulation of Pi in solution but less is known on how this accumulation affects the status of P onto the solid phase and the subsequent dynamics of P transfer at the solid-solution interface. Our objective was to determine the effect of tillage on the dynamics of Pr at the solid-solution interface in the topsoil. Soils were sampled (0-5 cm) during fall 2009 in a long term corn/soybean rotation under NT and mouldboard plough (MP) established since 1992. A 40 hour sorption/desorption experiment coupled with isotopic dilution labelling were conducted on soil suspensions (M/V:1/10) at steady state to describe the transfer of Pr. The kinetic Freundlich equation described precisely the transfer of Pr at the solid-solution interface but was influenced by the tillage system, yielding two distinct parameterizations: Pr=23.20Cp0.43t0.27 for the NT (r2=0.97), and Pr=19.90Cp0.42t0.30 for the MP (r2=0.99). These equations showed that the effect of NT on Cp after 17-years, induced higher quantities of Pr under NT compare to MP. These results are supported by values of the degree of P saturation of the top-soils which are higher under NT (10.15 ± 1.01 mmol kg–1. mmol kg–1) compare to MP (7.83 ± 0.89 mmol kg–1. mmol kg–1). The characteristics of the diffusive P supply derived from the models showed a modification of the dynamics of Pr at the solid-solution interface in the NT. The NT soil has a greater ability to supply P to the solution and therefore to maintain higher levels of Pi in the top-soil.
See more from this Division: S04 Soil Fertility & Plant Nutrition
See more from this Session: Phosphorus and Potassium Management: I